Detection of molecular characterization and antimicrobial susceptibility of photobacterium damselae strains in sea bass and sea bream

Objective: In this study, it was aimed that declaring of diagnosing of Photobacterium damselae and its subspecies, which are significant threat for gilthead sea bream and European sea bass aquaculture, with molecular technique and sensitivity to antibiotics. Material and Methods: The study materials were 100 dead gilthead sea bream (Sparus aurata) and European sea bass (Dicentrarchus labrax) which were suspected as Photobacterium damselae. P. damselae isolation was performed by using conventional, rapid diagnostic and molecular methods from internal organs of fish specimens, and antibiotic susceptibility was investigated by disk diffusion method. Results: While 26 (26%) Photobacterium damselae were isolated from the internal organs of gilthead sea bream specimens, any isolation from European sea bass specimens not performed. Total 26 (26%) P. damselae isolates were isolated by gilthead sea bream were identified by BD Phoenix diagnosis device. Isolated 26 (26%) P. damselae was confirmed by 16S rRNA PCR and subspecies seperation was performed by PCR using CPS and URE C genes. As result, 18 (69.23%) of the P. damselae strains were typified as P. damselae subsp. piscicida and the remaining 8 (30.77%) were as P. damselae subsp. damselae. All P. damselae subsp. piscicida isolates were 100% sensitive to gentamicin (10 µg), while both P. damselae subsp. piscicida and P. damselae subsp. damselae isolates were found to be 100% sensitive to ciprofloxacin (5 µg). Conclusion: With this research, Photobacterium damselae subsp. piscicida and Photobacterium damselae subsp. damselae which are important disease agents for both gilthead sea bream and European sea bass were diagnosed by molecular with species specific genes and their susceptibilities to some antibiotics were declared.